Skylights



R. A. BOYD July 25, 1961 SKYLIGHTS 2 Sheets-Sheet 1 Filed Jan. 2, 1957 ZONE 1H TRANSMITTQD Sour/4 FACE 3 L-FACE'd- INVENTOR. Passer A. Boyo ATTOENZYS.

United States Patent 2,993,409 SKYLIGHTS Robert A. Boyd, Ann Arbor, Mich., assignor to Owens- Illinois Glass Company, a corporation of Ohio Filed Jan. 2, 1957, Ser. No. 632,149 12 Claims. (CI. 88-60) This invention relates to the utilization of daylight for lighting the interior of buildings through an opening in a roof or ceiling.

A major problem in utilization of daylight through an opening in a roof or ceiling is that the direct sunlight from high altitude angles provides an excessive amount of light and heat. This condition is especially present during the summer months when the sun is at the higher altitudes.

In my copending application titled Skylights, Serial No. 295,730, filed June 26, 1952, now Patent No. 2,812,- 690, dated November 12, 1957, I propose a solution to this problem wherein the control of the transmission of daylight is achieved by interposing at least one sheet of light-transmitting material in generally horizontal position in the opening in the ceiling. Such a sheet preferably comprises one of the parallel sheets in a hollow glass block. In such a hollow block the air-glass interfaces are conventionally termed faces 1, 2, 3 and 4face 1 being the interface nearest the daylight, faces 2 and 3 being the interior interfaces and face 4 being the interface nearest the interior of the room.

As set forth in the aforementioned patent application, face 2 is provided with a series of parallel prisms extending in a generally east-west direction. The configuration of the prisms is such that sunlight from high altitude angles is substantially totally rejected by total internal reflection and sunlight from low altitude angles and light from the northern sky are transmitted by refraction through the prisms toward the interior being lighted.

In my copending application titled Skylights, Serial No. 358,277, filed May 29, 1953, now Patent No. 2,812,- 691, dated November 12, 1957, I have shown an improvement on the invention of the pending application, Serial No. 295,730 wherein the configuration of the prisms on face 2 is such that sunlight from high altitude angles is substantially totally rejected by total internal reflection in a plurality of prisms.

The constructions shown in my copending applications have proven very successful in utilizing daylight to light the interior of a room through an opening in a roof or ceiling. However, in certain instances and locations, it may be desirable to obtain a broader and more complete range of rejection than is possible by utilizing the constructions shown in the aforementioned applications.

It is therefore an object of this invention to providean improved skylight which rejects direct sunlight from high altitude angles and transmits sunlight from low altitude angles.

It is a further object of this invention to provide such a skylight which has a broad range of substantially total rejection of sunlight from high altitude angles.

In the drawings:

FIG. 1 is a diagrammatic representation of the results obtained by a skylight utilizing my invention.

FIG. 2 is a fragmentary cross sectional View, on a greatly enlarged scale, showing the prior art construction.

FIG. 3 is a fragmentary sectional view, on an enlarged scale, of a portion of the skylight embodying my invention.

FIG. 4 is a graph showing the percent light transmission at various altitudes.

Referring to FIG. 1, the skylight comprises a plurality of hollow blocks 11 of light-transmitting material such as glass mounted in a prefabricated panel 12. Each 2,993,409 Patented July 25, 19.61

block comprises parallel spaced sheets 13, 14 providing faces 1, 2, 3 and 4-face 1 being the interface nearest the daylight, faces 2 and 3 being the interior interfaces and face 4 being the interface nearest the interior of the room.

The construction shown in my copending application, Serial No. 358,277, provides a broader range of rejection of sun altitude angles. In this construction, as shown in 1G. 2, face 2 is formed with unsymmetrical prisms 15. Each prism 15 has a first surface 16 extending upwardly in a southerly direction and a second surface 17 extending upwardly in a northerly direction, the angle which the first surface forms with the plane of sheet 13 being less than the angle which the second surface 17 formed with the plane of sheet 13. As disclosed in this copending application, the angle b which surface 16 forms with the plane of sheet 13 is about 40 and the included angle P of each prism is preferably about but may range between 60 and 87". In this arrangement, a light ray L at a high altitude angle 0 is refracted at face 1 to a first surface 16 of a prism on face 2, thereafter reflected from the first surface 16 of the prism to a second surface 17 of the same prism, refracted through the second surface 17 of the prism to a first surface 16 of an adjacent prism, refracted through said first surface 16 of the second prism to a second surface 17 of the second prism, reflected at the second surface 17 of the second prism to face 1 and thereafter refracted at the surface of face 1 to the exterior.

In the arrangement shown in FIG. 2 where all the apexes of the prisms on face 2 are in a common plane parallel to the plane of the sheet of light-transmitting material on which the prisms are formed, it is possible that at certain altitude angles some of the light rays will not be totally rejected in the aforementioned manner. For example, a light ray L at an altitude angle a which strikes the second surface 17 of a prism in the area adjacent the apex of the prism may be reflected to the first surface 16 of the prism and refracted from the first surface 16 but, in passing toward the adjacent prism, light ray L may not be intercepted by the second surface 17 of the adjacent prism and therefore will not be rejected. Similarly, a light ray L at an altitude angle a which strikes the first surface 16 of a prism adjacent the base of the prism may be reflected toward the second surface 17 of the prism, refracted through second surface 17 to the first surface 16 of the adjacent prism and refracted from the first surface 16 of the adjacent prism; but light ray L may not be intercepted by the second surface 17 of the adjacent prism and therefore will not be totally rejected but will pass through sheet 13.

Referring to FIG. 2, it can be seen that light rays, such as light ray L which are transmitted at high altitude angles and which strike the surfaces of the prisms on face 2 centrally thereof are substantially totally re jected by total internal reflection through a pair of prisms. On the other hand, light rays L at the same altitude angles which strike the surfaces of the prism adjacent the apexes of the prism are not transmitted to the adjacent prisms and therefore are lost in the air adjacent the prisms. Light rays L at the same altitude angles striking the surfaces of the prism adjacent the bases of the prism are transmitted through the glass and are not totally reflected through a pair of prisms. For example, for a particular altitude angle a the light designated portions A and C will be substantially totally rejected while the light rays designated portions B and D will be lost, the light portions B being lost in the air and the light portion D being lost in the glass.

According to my invention, a substantial portion of the light which is lost in the constructions shown in FIG.

2 is rejected so that a broader range of light rejection is obtained.

Referring to FIG. 3, according to my invention, face 2 is provided with a plurality of primary prisms 20 and secondary prisms 21, 22, 23 and 24. Prism 20 has the southerly slope thereof formed with an upwardly and southerly extending surface 25 while the northern slope thereof has the smaller prisms 21, 22, 23 and 24 thereon. In FIG. 3, the surfaces on the southerly slope of the primary prism 20 are designated as follows: the northerly extending surfaces are 26, 27, 28, 29 and 36 and the southerly extending surfaces are 31, 32, 33 and 34.

The included angle P formed between the surfaces of each prism is the same and is preferably approximately 75 but may range between 60 and 87. The bases of the small or secondary prisms 2024 lie in a common plane which forms an angle x with the horizontal plane of sheet 13. The apexes of these prisms lie in a common plane which forms an angle y with the horizontal plane of sheet 13.

I have determined that when the angle P is equal to 75 x is greater than y; when the angle P is less than 75, x is less than y; and when the angle P is greater than 75, x is greater than y.

Referring to FIG. 3, a light ray L striking face 1 at an altitude angle a is refracted through face 1 to surface 29 of prism 23 and reflected from surface 29 to surface 33 of prism 23, refracted through surface 33 of prism 23 to surface 28 of prism 22, refracted by surface 28 to surface 25 of primary prism 20, reflected by surface 25 to face 1 and refracted to face 1 and the exterior. This This light ray L is thus totally rejected. A light ray L at an altitude angle a is reflected by surface 33 of prism 23, refracted through surface 29 of prism 23, refracted by surface 34 of prism 24, and reflected by surface 30 of prism 24 toward face 1 and the exterior.

A light ray L at an altitude angle a is refracted through face 1 to surface 27 of prism 22, reflected by surface 27 of prism 22 to surface 28 of prism 22, refracted by surface 28 of prism 22 to surface 25' of the adjacent primary prism refracted by surface to surface 30 of secondary prism 24', reflected by surface 33' toward face 1 and refracted by face 1 toward the exterior.

The effect of providing the primary and secondary prisms is to broaden the range through which light rays of the higher altitude angles are rejected.

In the case of glass having an index of refraction of 1.52, I have found the following examples of prism construction to give satisfactory results:

Referring to FIG. 4 which shows the percent transmission at various sun altitudes of faces 1 and 2 utilizing various prism constructions, the curve shown in solid lines represents the percent transmission obtained when the prior art construction shown in FIG. 2 is used and P equals 75 and b equals 40.

Curve I represents the percent transmission when the prism construction set forth in Example I above is used. Curve II represents the percent transmission when the prism construction set forth in Example II above is used.

It can be seen that with the prior art prism construction, substantially total rejection occurs at sun altitudes ranging between 55 and 65. With the prism construction of my invention, the substantial total rejection occurs for sun altitudes ranging between 45 and in curve I and for sun altitudes ranging between 55 and in curve II. Thus, in hollow blocks utilizing the prism construction of my invention the range of sun altitudes at which substantial total rejection of the sunlight occurs is substantially broadened, particularly at the higher sun altitudes.

I claim:

1. In a construction for utilizing daylight to light an interior, the combination comprising a room having an opening in the ceiling thereof and a sheet of light-transmitting material interposed in a generally horizontal position between the daylight and the interior being lighted, said sheet having a series of unsymmetrical parallel prisms on the face thereof nearest the interior, the axes of said prisms extending in a generally east-west direction, said prisms including primary prisms having a first surface extending upwardly in a southerly direction and a second surface extending upwardly in a northerly direction, said second surface being formed with a plurality of secondary prisms each of which has a surface extending upwardly in a southerly direction and a surface extending upwardly in a northerly direction, the angles which said northerly extending surfaces form with a horizontal plane being greater than the angles which said southerly extending surfaces form with a horizontal plane, the included angle between said surfaces being such that sunlight from high altitude angles is substantially totally rejected by total internal reflection within a plurality of said prisms and sunlight from low altitude angles and light from the northern sky are transmitted by refraction through the prisms toward the interior being lighted, the apexes of said secondary prisms lying in a common plane which forms an angle with a horizontal plane and the bases of said secondary prisms lying in a plane which forms an angle with the plane containing the apexes of said secondary prisms.

2. The combination set forth in claim 1 wherein the included angle between said southerly extending surface and said northerly extending surface of each prism ranges from 60 to 87.

3. The combination set forth in claim 1 wherein the included angle between said southerly extending surface and said northerly extending surface of each prism is approximately 75 and the angle which the common plane containing said bases of said secondary prisms forms with the horizontal plane is greater than the angle formed by the common plane containing the apexes of the secondary prisms with a horizontal plane.

4. The combination set forth in claim 1 wherein the included angle between said southerly extending surface and said northerly extending surface of each prism is greater than 75, and the angle which the common plane containing said bases of said secondary prisms forms with the horizontal plane is less than the angle formed by the common plane containing the apexes of the secondary prisms with a horizontal plane.

5. The combination set forth in claim 1 wherein the included angle between said southerly extending surface and said northerly extending surface of each prism is less than 75 and the angle which the common plane containing said bases of said secondary prisms forms with the horizontal plane is greater than the angle formed by the common plane containing the apexes of the secondary prisms with a horizontal plane.

6. The combination set forth in claim 1 wherein said sheet of light-transmitting material comprises one of the walls of a glass block.

7. A skylight comprising a sheet of light transmitting material adapted to be interposed in a substantially horizontal position between the daylight and the interior being lighted, said sheet having a series of unsymmetrical parallel prisms on one face thereof, the axes of said prisms extending longitudinally of said sheet, said prisms including primary prisms having a first surface extending toward the plane of said sheet and a second surface extending in the opposite direction toward the plane of said sheet, said second surface being formed with a plurality of secondary prisms each of which has a first surface parallel to the first surface of said primary prism and a second surface parallel to the second surface of said primary prism, the angle which each said second surface of the secondary prism forms with the plane of said sheet being greater than the angle which each said first surface forms with the plane of said sheet, the included angle between said first and second surfaces of said prism being such that light rays directed against the other face of said sheet at small angles to and on one side of longitudinal planes normal to the planes of the sheet are substantially totally rejected by total internal reflection and light rays directed against the other face of said sheet at the remaining angles on the same side of the normal longitudinal planes and light rays directed against said face on the other side of said normal longitudinal planes are transmitted by refraction through said sheet, the apexes of the secondary prisms lying in a common plane which forms an angle with the plane of said sheet and the bases of the secondary prisms lying in a plane which forms an angle with the plane containing the apexes of the secondary prisms.

8. The combination set forth in claim 7 wherein the included angle between the first surface and the second surface of each prism ranges from to 87.

9. The combination set forth in claim 7 wherein the included angle between the first surface and the second surface of each prism is approximately and the angle which the common plane containing said bases of said secondary prisms forms with the plane of the sheet is greater than the angle which the common plane containing the apexes of the secondary prisms forms with the plane of said sheet.

10. The combination set forth in claim 7 wherein the included angle between the first surface and the second surface of each prism is greater than 75, and the angle which the common plane containing the bases of said secondary prisms forms with the plane of the sheet is less than the angle which the common plane containing the apexes of the secondary prisms forms with the plane of said sheet.

11. The combination set forth in claim 7 wherein the included angle between the first surface and the second surface of each prism is less than 75, and the angle which the common plane containing said bases of said secondary prisms forms with the plane of said sheet is greater than the angle which the common plane containing the apexes of the secondary prisms forms with the plane of said sheet.

12. The combination set forth in claim 7 wherein the sheet of light transmitting material comprises one of the walls of a glass block.

References Cited in the file of this patent UNITED STATES PATENTS 458,850 Jacobs Sept. 1, 1891 586,219 Basquin July 13, 1897 650,209 White May 22, 1900 709,849 De Man Sept. 23, 1902 719,066 Wadsworth Jan. 27, 1903 1,652,347 Champeau Dec. 13, 1927 2,097,738 Oita Nov. 2, 1937 2,419,267 Lenke Apr. 22, 1947 2,545,906 Watkins Mar. 20, 1951 FOREIGN PATENTS 16,541 Great Britain of 1897 556,218 Great Britain Sept. 24, 1943 754,619 Great Britain Aug. 8, 1956 

